This invention relates to flexible hose couplings, particularly couplings suitable for use with reinforced hose, a method of making such couplings, and die apparatus for making the couplings.
A variety of hose couplings for flexible rubber and plastic hoses are known including couplings suitable for textile reinforced and metal reinforced hose. In many cases these couplings comprise two main members, one of which is a nipple or end fitting having a portion thereof that is inserted into the end of the hose, and the other of which is a metal ferrule or sleeve member that extends about the exterior of the hose end. Often the ferrule is mechanically connected to the nipple member such as by means of threads or by an internal rim formed on one end of the ferrule, which end is driven into a circumferential groove formed in the nipple member. The ferrule or outer sleeve is made crimpable. By using a die set, the ferrule can be crimped or forced inwardly to clamp the hose end tightly between the ferrule and the nipple member.
U.S. Pat. No. 3,835,891 which issued Sep. 17, 1974 to Compoflex Company Limited is illustrative of a high pressure flexible hose developed in recent years and employing inner and outer helical wires for reinforcement. This hose may comprise several tubular layers of a plastics material which extends between the helical wires. These flexible layers can, for example, comprise fluorinated ethylene propylene copolymer. The inner helical wire is preferably coated with fluorinated ethylene propylene copolymer of Teflon(trademark). For the conveyance of chemicals, layers of polypropylene fabric and polypropylene film are laid on the copolymer. The hose can be covered on its exterior with a coating of PVC (polyvinylchloride). By the use of helical wires on the inside and outside, this type of hose is capable not only of withstanding high internal pressures but it is also capable of full suction.
A metal coupling for the aforementioned wire reinforced hose is known in the industry, this coupling comprising a nipple member and a surrounding ferrule or sleeve. An external two start thread is formed on a section of the nipple having a reduced diameter. One of the grooves of this thread receives the inner helical wire of the hose while the other groove accommodates the inward bends of the flexible, tubular portion of the hose. The nipple is inserted into the end of the hose by a threading operation. An iron of steel ferrule is placed around the hose end and a flexible seal can be arranged adjacent the hose end between the nipple and the ferrule. The ferrule is provided with an inwardly extending flange or rim at one end. In addition to or instead of the aforementioned seal member, epoxy or other sealant material can be inserted between the ferrule and the end of the hose in order to provide a seal in the completed hose coupling. Once the sealing material is in place, the ferrule is then reduced in diameter by a suitable swaging process so that the end of the hose is compressed between the inside of the ferrule and the nipple. The swaging process results in a mechanical connection which helps to prevent the coupling from coming off the end of the hose. This connection is created between the inner helical wire and the threads or grooves formed on the exterior of the nipple.
Difficulties have been encountered in the art with the aforementioned coupling designed for a wire reinforced hose. One difficulty with this coupling and its method of manufacture arises from the tendency of the ferrule to bulge out during the manufacturing process. A bulging of the ferrule can result in seal failure. Another known difficulty is that the epoxy or secondary seal used in the coupling can sometimes be forced out of the space between the ferrule and the hose, leaving gaps or weaknesses in the seal.
U.S. Pat. No. 3,413,020 issued Nov. 26, 1968 to Samuel Moore and Company describes a fitting designed for composite tubing suitable for high pressure applications. The hose can be a polymeric composite tubing that has an inner helical wire extending about the interior of the tubing and laid along a helical cavity. For purposes of manufacturing the fitting, the last few turns of the helical wire are removed by means of pliers and wire cutters. The nipple or inner sleeve is formed with a helical, external thread which is threaded into the helical cavity formed in the hose end. The hose fitting is completed by an outer sleeve or ferrule having a series of internal teeth. These teeth engage against the outside of the hose end by crimping the outer sleeve inwardly. The ferrule is also held in place on the inner sleeve or nipple by means of threads formed at one end of the ferrule.
It is an object of the invention to provide a reinforced hose coupling which provides a secure connection between a hose end and the fitting itself and which is relatively inexpensive to manufacture. According to one aspect of the invention, the reinforced hose coupling is constructed for use with a reinforced hose end having an exterior helical wire. By projecting the end of the helical wire through holes formed in a depression in the side of the ferrule, not only a further mechanical connection between the hose end and the fitting is provided, but also an indicator that the hose coupling is in good condition for use.
It is a further object of the invention to provide a reinforced hose coupling wherein no separate sealant such as epoxy is required to seal the joint between the hose end and the fitting. The flexible tubular layers of the hose end extend beyond any helical wire that reinforces the hose and by clamping the extended tubular layers between the ferrule and the nipple member, a fluid tight seal can be formed.
It is an additional object of the invention to provide a method for making a coupling for reinforced flexible hose that has a helical wire extending about its interior. This manufacturing method can be carried out quickly using a first die and at least one follower die of smaller diameter on the metal ferrule of the coupling. It is the follower die or dies which cause the extension of the tubular layers to be clamped tightly between the ferrule and the nipple member.
According to one aspect of the invention, a reinforced hose coupling comprises an end-fitting having first and second, axially extending sections, the first section comprising a connecting element and the second section providing a nipple element having external grooves formed. thereon. A metal ferrule is mounted on and about the nipple element and is connected to the end fitting. This ferrule has a generally cylindrical wall and an external depression formed in a side of this wall and projecting radially inwardly towards the nipple element. Two holes are formed in the depression and through the wall. A reinforced hose end having flexible tubular layers is crimped between the ferrule and the nipple element. This hose end has a helical wire extending about the exterior of the flexible tubular layers. An end piece of this wire extends through one of the holes, across the depression and back through the other hole.
Preferably the depression is elongate in the circumferential direction of the ferrule and the two holes are formed in opposite ends of the depression.
According to another aspect of the invention, a reinforced hose coupling comprises an end fitting having first and second axially extending tubular sections, the first and second sections being separated by a circumferential groove formed in an exterior surface of the end fitting. The first tubular section comprises a connecting element and the second section has an external helical groove that spirals about its circumference. There is also provided a flexible hose end comprising flexible tubular layers of plastics or rubber material and an inner helical wire extending about the interior of the tubular layers. The second section of the end fitting extends into the hose end so that the helical wire extends along and in the helical groove and circumferentially about the second section. An axial extension of the tubular layers extends beyond an adjacent end of the helical wire and along the exterior of the second section. The coupling includes a metal ferrule mounted on the hose end and extending around an end section of the helical wire and the axial extension of the tubular layers. This ferrule has an internal rim at one end which extends into the circumferential groove in order to mechanically connect the ferrule to the end fitting. The axial extension of the tubular layers is clamped between the ferrule and the end fitting, thereby forming a fluid tight seal.
In a preferred embodiment of this coupling, the hose end also has an outer helical wire extending about the exterior of the tubular layers and ending near the adjacent end of the inner helical wire.
According to a further aspect of the invention, there is provided a method of making a coupling for reinforced flexible hose, which method includes providing a flexible hose reinforced by means of a helical wire extending about the interior of the hose and having an end on which a coupling is to be provided. This hose includes flexible tubular layers which axially extend beyond an end of the helical wire at the end of the hose. A metal ferrule is placed over the hose and adjacent to the one end of the hose, this ferrule being formed with a circumferentially extending internal rim at an end of the ferrule closest to the one end of the hose. An end fitting is inserted into the one end of the hose, this fitting having first and second axially extending sections, the first section comprising a connecting element that projects from the one end of the hose and the second section providing a nipple element with external grooves formed thereon. The nipple element is placed in the hose so that the helical wire extends along the external grooves. The end fitting has an external, circumferential groove formed therein and spaced from the ends thereof. The metal ferrule is swaged with a first die so as to drive the internal rim into the circumferential groove and mechanically connect the ferrule to the end fitting. This step also clamps a portion of the helical wire in the external grooves of the nipple element which secures the hose to the end fitting. The metal ferrule is then swaged with a follower die of smaller diameter than the first die. This step clamps the tubular layers which extend beyond the end of the helical wire tightly between the ferrule and the end fitting in a sealing manner.
In a preferred version of this method, the end fitting is inserted into the one end of the hose by screwing the fitting relative to the hose end in order to thread the helical wire into the external grooves.
According to still another aspect of the invention, there is provided an apparatus for making a coupling for flexible hose reinforced by means of a helical wire extending about the interior of the hose, the apparatus includes a supporting device for holding one end of the hose and a generally cylindrical metal ferrule arranged over an end section of the hose during operation of the apparatus. The ferrule is formed with a circumferentially extending internal rim located at an end of the ferrule closest to said one end of the hose and having an initial first external diameter. A first annular die forms a circular die opening having a minimum diameter a little smaller than said first external diameter. A second annular die has a minimum diameter a little smaller than said minimum diameter of the first die. A mounting arrangement is also provided for rigidly connecting each of the first and second dies to a hydraulic ram so that each die can be driven linearly along the exterior of the ferrule starting at the end of the ferrule having the internal rim. The swaging action of the first die causes the end section of the hose, including an end portion of the helical wire, to be clamped firmly between the ferrule and an end-fitting positioned within the end section of the hose, and causes the internal rim to be deformed radially inwardly into an annular groove formed around the end-fitting. A subsequent swaging action with the second die causes a relatively short end portion of the hose having no helical wire extending about its circumference to be sealingly clamped between the ferrule and the end-fitting, this further swaging action occurring only along a section of the ferrule immediately adjacent said short end portion of the hose.
According to yet another aspect of the invention, a die apparatus for swaging a tubular metal body comprises a split die ring forming a circular opening and made up of two semi-annular die sections each having a radially inner surface for engaging and shaping the metal body and a radially outer surface which in radial cross-section extends at an acute angle to a central axis of the circular opening. An annular die body surrounds and supports the die ring, this die body having an annular, sloping engagement surface in contact with the radially outer surface of the die ring and parallel thereto. The die body has a number of pin passageways that extend radially through the die body. A number of holding pins each extend through a respective one of the pin passageways and have a head on a radially outer and thereof. A rotatable cam ring extends about the die body and has a number of slots formed therein and spaced about the circumference of the cam ring. Each of said slots extends in a generally circumferential direction and has a respective one of the pin heads captured therein. The pins can be moved radially outwardly by rotation of the cam ring from a first position where inner ends of the pins engage and hold the split die ring in the die body to a second position where the pins are disengaged from the split die ring.
Further features and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings.